Effect of BaO on the viscosity and structure of fluorine-free calcium silicate-based mold flux

Viscosity and structure evolution of bearing‐BaO slag melt with the low CaO/SiO2 mass ratio of 0.7

“…At present, the effect of BaO on the viscosity of many slag systems has been investigated, but the obtained results are not consistent. Gao et al 4 studied the effect of BaO on the viscosity and structure of CaO-Al 2 O 3 -based mold flux by substituting CaO with BaO, and pointed out that both viscosity and the apparent activation energy for viscous flow tended to increase with a rise of BaO content, which was consistent with the work done by Wang et al 5 and Li et al 6 Piao et al 7 measured the viscosity of fluorine-free CaO-SiO 2 -based mold flux, and found out that the viscosity of mold flux decreased with BaO concentration increasing from 3.0 wt.% to 11.0 wt.%. Furthermore, Piao et al 8 also found that the addition of BaO could reduce the viscosity of the fluorine-free CaO-Al 2 O 3 -TiO 2 -based mold flux with the fixed CaO/Al 2 O 3 ratio.…”

“…For the dissolution behavior of BaO in high‐temperature melt, Piao et al 7 showed that the average lengths from Al‐O, Si‐O, Ba‐O, and Ca‐O bonds were about 1.75Å, 1.65Å, 2.70Å, and 2.25Å according to the molecular dynamics (MD) simulation, indicating that Ba‐O bond was weaker compared with Ca‐O, Si‐O, and Al‐O bonds in slag melt, which meant that BaO was easier to dissociate into Ba 2+ and O 2− . For present experimental slag, the BaO/Al 2 O 3 molar ratio was far less than 1.0, which implied that the Ba 2+ dissociated from BaO was mainly used for compensating [AlO 4 ]‐tetrahedron unites because of its lower field strength.…”

“…Furthermore, Piao et al 8 also found that the addition of BaO could reduce the viscosity of the fluorine‐free CaO–Al 2 O 3 –TiO 2 ‐based mold flux with the fixed CaO/Al 2 O 3 ratio. In addition, Xing et al 9 and Xu et al 10 investigated the effect of BaO on the viscosity of blast furnace slag and revealed that BaO could induce the higher degree of polymerization (DOP) and higher viscosity of slag melt, which was inconsistent with the work of Piao et al 7–8 . This phenomenon may be explained by the mixed alkali effect.…”

Influence of Al₂O₃/SiO₂ and BaO/Al₂O₃ Ratios on Rheological and Crystallization Behavior of CaO–BaO–Al₂O₃-Based Mold Slags

“…Hence, it is essential to understand the effect of the substitution of SiO 2 by Al 2 O 3 on the crystallization of CaO-Al 2 O 3 -based mold slag, and the substitution of Al 2 O 3 by BaO on slag properties was also investigated, with BaO helping to restrain slag crystallization and lower the slag viscosity. [28][29][30] Moreover, the effect of the substitution of Al 2 O 3 for SiO 2 and BaO for Al 2 O 3 on the rheological and crystallization behavior of the current CaO-BaO-Al 2 O 3 -based mold slag was not well understood.…”

EFFECT OF THE CaO-MgO-Al₂O₃-SiO₂ GLASS COMPOSITION ON THE MICROSTRUCTURE AND RHEOLOGICAL PROPERTIES FROM A MOLECULAR DYNAMICS SIMULATION

“…Nguyen VanHong et al [13] discussed that Ca ions were usually bound to the glass network structure by providing a non-bridging oxygen and by balancing negative charges. Li et al [14][15][16][17] reported the influence of CaO and MgO in the melt of the CaO-MgO-Al 2 O 3 -SiO 2 system. They observed that MgO was more likely to destroy the glass structure than CaO.…”